Books about Abraham Lincoln often tell us as much about the authors and their times as their subject. Although Lincoln died a century and a half ago, we see him as our contemporary. As the Great Emancipator, who freed the slaves with a stroke of his pen, Lincoln enables readers to congratulate themselves about society's progress toward racial justice. When optimism about race relations wanes, so does adulation of Lincoln. Fred Kaplan, who insists that even Lincoln could never bring himself to embrace racial equality, concludes his new book with references to Ferguson, white nationalism, and the rise of the alt-right.

The author of several well-regarded biographies, including one of Lincoln, Kaplan is at his best in penning brief portraits of a diverse cast of characters. Some, like Lincoln's political idol Henry Clay and the abolitionist orator Wendell Phillips, are widely known. Others, including the black abolitionist H. Ford Douglas and Usher Linder, a pro-slavery Illinois lawyer whom Lincoln befriended, are unfamiliar even to specialists in Civil War history. These vignettes succeed in highlighting the wide array of responses to the slavery issue in Lincoln's America.

The book, however, never quite gels. As the bifurcated title suggests, it lacks a clear focus. In addition, there are numerous historical errors, some trivial (the Northwest Ordinance was adopted in 1787, not 1795) but many egregious. Instead of giving African-Americans the right to vote in 1821, as Kaplan states, New York in fact disfranchised nearly all of them. It is astonishing to read that Tennessee, one of the eleven states of the Confederacy "never left the Union" or that the Compromise of 1850 (rather than the Kansas-Nebraska Act of 1854) repealed the Missouri Compromise, a milestone on the road to civil war.

Along with Lincoln, the book's other key figure is John Quincy Adams. Beginning in 1830, after serving a term as president, Adams was elected several times to the House of Representatives, where he led the fight against the "gag rule" that barred discussion of abolitionist petitions. Kaplan is mostly interested in Adams in order to contrast him, an "antislavery activist," with Lincoln, an "antislavery moralist"– someone who spoke against slavery but failed to take action against it. Adams believed in the citizenship of free blacks; Lincoln did not. Lincoln "put all his hopes" for ending slavery in the American Colonization Society, which advocated encouraging or requiring free blacks and emancipated slaves to emigrate to Africa, while Adams considered colonization impractical and unethical. Adams insisted that in a war the president could invoke his power as commander-in-chief to abolish slavery; Lincoln only moved toward emancipation slowly and reluctantly, and when he did issue the Emancipation Proclamation, he exempted three-quarters of a million slaves in parts of the Confederacy and in the four border slave states that remained in the Union. Lincoln's reluctance to act decisively against slavery, Kaplan argues, reflected both personal qualities – "compromise and gradualism were in his blood" – and a strong devotion to the Constitution, despite its provisions protecting slavery. But the deepest reason for his hesitation was racism: Lincoln believed that America "was and always should be a white man's country."

Kaplan is correct to direct attention to Lincoln's strong advocacy of colonization during the 1850s and the first two years of the Civil War, something many admirers downplay or ignore. But as a full portrait of Lincoln's views on slavery and race, the account is, to say the least, one-dimensional. Kaplan's treatment of Lincoln's relationship with abolitionists, who demanded an immediate end to slavery, is a case in point. Lincoln was not an abolitionist and never claimed to be one. But it is untenable to write, as Kaplan does, that Lincoln "detested" abolitionists and "wanted nothing to do" with them. Lincoln considered himself part of an antislavery movement that also included abolitionists. He understood that without their effort to change public opinion, his own more moderate antislavery politics, which focused on preventing slavery from expanding, not its abolition, would be impossible.

In 1856, Republicans in northern Illinois nominated Owen Lovejoy to run for Congress. The brother of the antislavery editor Elijah P. Lovejoy, who had been murdered by a mob in 1837, Owen Lovejoy was himself an outspoken abolitionist. A group of conservative Republicans, including close friends of Lincoln's, proposed to put forward an independent candidate. Lincoln instructed them not to do so, not simply because he believed in party unity, but because of the "great enthusiasm for Lovejoy" that his supporters would "carry into the contest." To use a modern idiom, Lincoln understood that abolitionists were part of the Republican party's base. And despite sharp criticisms of Lincoln, most supported his election in 1860. As Manisha Sinha notes in her recent history of abolitionism, Wendell Phillips greeted his victory by exulting, "for the first time in our history, the slave has chosen a president." All this is absent from "Lincoln and the Abolitionists."

When it comes to the fraught question of Lincoln's views on race, Kaplan again oversimplifies a complex situation. He rightly notes that Lincoln's embrace of colonization reflected pessimism that blacks could ever enjoy equality in the United States. Kaplan quotes Lincoln's disavowal, in his 1858 debates with Stephen A. Douglas, of black suffrage, jury service, and other rights. But he dismisses as unimportant Lincoln's insistence in the same debates that blacks were entitled to the inalienable natural rights enumerated in the Declaration of Independence – rights that Douglas insisted applied only to whites.

Lincoln undoubtedly shared many of the prejudices of his era. During his career, however, he actually said very little about race. Unlike contemporaries, he did not give orations on the glories of the white race. Unlike Clay and other colonizationists, he never berated free blacks as a dangerous, criminally-minded class. Lincoln was the first president to meet with blacks in the White House. The point is not that Lincoln was a modern egalitarian, but that unlike incorrigible racists such as his successor Andrew Johnson, he was capable of growth. As the war progressed, Lincoln's racial outlook evolved. By the end of his life he was advocating suffrage for educated blacks and black soldiers – this at a time when only six northern states allowed any African-Americans to vote.

Not surprisingly, Kaplan ends on a pessimistic note. When he died, Lincoln "knew that his beloved country had entered into a century and more of racial misery." (How Kaplan knows that Lincoln "knew" this remains unexplained.) The effort during postwar Reconstruction to secure civil and political equality for the former slaves, Kaplan insists, was doomed from the start. Had Lincoln lived, it would have made no difference. Racism, the outgrowth "of tribalism, of identity politics, of us against them, in every area of human life," is too deeply ingrained in American society, indeed in human nature.

Kaplan, in other words, employs racism as a deus ex machina – something that exists outside of history but that can be invoked as the ultimate explanation for historical events. Yet if racism is constant and immutable, how did millions of northerners come to embrace emancipation and the laws and constitutional amendments of Reconstruction? A better approach is to see racism as part of history. Racism, like anything else, rises and falls over time, and sometimes people change.